Coating composition for wooden concrete forms and method of preparing wooden forms having improved concrete anti-sticking characteristics

ABSTRACT

WOODEN CONCRETE FORMS HAVING IMPROVED CONCRETE ANTISTICKING CHARACTERISTICS ARE OBTAINED BY APPLYING TO THE CONCRETE-CONTACTING SURFACES OF THE FORMS A COATING COMPOSITION CONSISTING ESSENTIALLY OF A MIXTURE OF (1) A HYDROCARBON RESIN DERIVED FROM A CYCLIC OLEFIN SUCH AS A RESSIN OF DICYCLOPENTADIENE; (2) MINERAL OIL HAVING A VISCOSITY OF ABOUT 100 TO ABOUT 1000 SUS AT 100*F.; (3) PARAFFIN WAX HAVING A MELTING POINT OF ABOUT 120* TO ABOUT 155*F.; AND (4) A HYDROCARBON DISTILLATE SOLVENT, E.G., STODDARD SOLVENT, KEROSENE, ETC.

United States 3,600,348 COATING COMPOdITION FOR WOODEN CON- CRETE FORMS AND METHOD OF PREPARING WOODEN FORMS HAVHNG IMPROVED CON- CRETE ANTI-ST'HCKING (IHARACTERISTICS lEarl lL. Humphrey, Verona, Pm, assignor to Gulf Research & Development Company, Pittsburgh, Pa. No Drawing. Filed Sept. 24, 1969, Ser. No. 860,782 Int. Cl. C08f 45/52; B29c 1/04 US. Cl. 26028.5A 12 Claims ABSTRACT OF THE DISCLOSURE This invention relates to a coating composition for wooden concrete forms, and to a method of preparing wooden concrete forms having improved concrete antisticking characteristics. More particularly, the invention relates to a composition for applying to wooden concrete forms designed for construction Work where repeated reuse of forms is normally practiced.

Forms made of wood, especially plywood, have long been used in conrete construction to hold the concrete in place until hardening of the concrete occurs. For obvious economic reasons it is desirable to remove the forms from the concrete after hardening occurs and thereafter reuse the forms for further molding purposes. Unfortunately, fresh concrete and untreated wood tend to adhere to each other making removal of the forms difiicult. In some instances the surface of the forms adhere so tightly to the concrete that both the surface of the form and the face of the concrete are damaged in removing the form. In addition to the adherence of the wood and concrete to each other, untreated wood can adsorb water so readily from wet concrete that a thin layer of concrete adjacent to the surface of the wooden form loses water before proper hydration of the cement can occur. In such instances, the surface of the concrete will be dusty or sandy. Such imperfectly hydrated surfaces are subject to deterioration upon exposure to normal atmospheric conditions. Still further, as untreated wooden forms adsorb water the hard and soft portions of the grain in the wood swell unequally. The result of this unequal swelling is that the face of the concrete reflects the grain of the Wood. Reflection of the wood grain in the surface of the concrete is often unsightly. To eliminate the undesired reflection of the wood grain in the hardened concrete and to obtain a more uniform finish, it is necessary to plaster the grained concrete surface with mortar or to rub the grained concrete surface with an abrasive. Either of these methods is costly and time consuming. In those instances when the concrete adheres to the surface of wooden forms, the concrete must be removed from the forms before they are reused. The removal of the concrete from the forms is costly and time consuming and frequently results in damage to the surface of the forms.

In an eifort to eliminate the water adsorption characteristics and to reduce the adherence of concrete to the surface of wooden forms, it has heretofore been proposed to coat the wood surface against which the concrete is cast with various coating compositions such as mineral 3,600,348 Patented Aug. 117, 197i oils, fatty oils, water-in-oil emulsion and other oleaginous substances. While the prior coating compositions have been partially satisfactory, considerable difliculty has been encountered in obtaining a composition which can be readily applied to the surface of wooden forms, will permit easy stripping of the forms and will give a concrete surface of desired smoothness.

It is an object of the present invention to provide a coating composition for ready application to the surface of a wooden form for molding concrete which will result in a molded concrete the surface of which is smooth and free from dust and has a minimum reflection of the grain of the wood used in the form. It is a further object of the invention to provide a coating composition which when applied to the surface of a wooden form used in molding concrete will result in easy stripping of the form from the hardened concrete with a minimum amount of concrete adhering to the surface of the form. These and other objects and advantages achieved by this invention will become apparent as the invention is more fully described hereinafter.

I have found that a wooden concrete form having improved concrete anti-sticking characteristics is obtained by applying to the concrete-contacting surface of the form a coating composition consisting essentially of a mixture of a hydrocarbon resin, mineral oil, paraffin wax and a hydrocarbon distillate as a solvent. The coating may be applied to the surface of the wooden form by any conventional method including spraying, brushing and rolling. The protective coating which results from using a composition of the invention is relatively thin, the thickness of a single coating normally averaging less than about 0.005 inch. Heavier films can be obtained by employing a minimum amount of solvent or by applying two or more coats.

The resin employed in the composition of the invention comprises a hydrocarbon resin derived from a cyclic olefin and has a melting point of about 50 to about 300 F. Examples of cyclic olefins from which suitable hydrocarbon resins are made include cyclopentadiene, dicyclopentadiene, cyclohexadiene and vinyl cyclohexene. The hydrocarbon resin is employed in amounts of about 15 to about 40 percent by weight of the total composition.

The mineral oil which is employed in the composition of the invention can be either a refined or semi-refined paraffinc, naphthenic or asphalt base oil. If desired, a blend of oils of suitable viscosity can be employed instead of a single oil, by means of which any desired viscosity may be secured. The oil or blend or oils is preferably one having a viscosity of about to about 1000 Saybolt Universal seconds at 100 F., a flash point (ASTM D92) above about 335 F., a fire point (ASTM D92) above about 370 F. and a pour point (ASTM D97) of about -20 to about +l0 F. If the viscosity of the mineral oil is outside the range of about 100 to about 1000 SUS at 100 F., the coating composition does not have the desired flow property. Desired non-flammability properties in the coating composition require the use of a mineral oil having a flash point above about 335 F. and a fire point above about 370 F. The mineral oil content of the composition of the invention comprises about 5 to about 25 percent by weight of the total composition.

The wax employed in the composition of the invention comprises paraffin wax having a melting point of about to about F. The Wax can contain a small amount of oil provided the desirable characteristics of the wax are not lost. Preferably, the wax contains not more than about 0.5 percent by weight of oil. The paratiin wax comprises about 10 to about 15 percent by weight of the total composition. A preferred embodiment of the invention utilizes about 12 to about 13 percent by weight of paraffin wax having a melting point of about 120 F The data in Table I clearly indicate the utility of compositions of the invention, i.e., Compositions E to K. It will be noted that the uncoated panels gave a concrete slab, the surface of which showed a reflection of the little or no reflection of the plywood grain. The amount of concrete which adhered to the plywood panel was quite small, varying from none up to only 0.32 gm./ sq. ft.

In order to illustrate the importance of using a hydroplywood grain and was rough and dusty. While the uncarbon resin derived from a cyclic olefin, comparative coated panels were easy to remove, a considerable amount compositions were tested using resins derived from cyclic of concrete (3.8 8 gm./sq. ft.) adhered to the panels. olefins and other resins including wood rosin, a limited When the plywood panels were coated only with minrosin and a saturated resin. The make-up and test results eral oil (Composition A), the surface of the concrete obtained with the comparative compositions are shown was smooth and free from dust but showed a reflection 10 in Table II.

TABLE II Composition E L M N O P Q,

285 F., Piceodiene 2285) Dicyclopentadiene resin (melting point,

50 F., Piccodiene 2050") Vinyl cyelohexene resin (melting point,

266 F., Betaprene B-130) Wood rosin Limed rosin Saturgted resin (Neville Resin LX- 78 Mineral oil (29.6 API gravity; 300 SUS at 100 F.; flash point, 460 F.; fire point, 620 F., pour point, +10 E). 10.0 Paraffin wax (melting point, 120 F.) 10. 0 Stoddard solvent (47.1 API gravity; 50% over at 340 F.; end boiling point of 382 F.; flash point, 110 F.) 62 0 Concrete form test:

Ease ofrernoval of form Easy Easy Easy Easy Easy Easy Easy.

Concrete stuck to form, gm./sq. it. 0.12

.72.... Appearance of concrete Smooth.-. Smooth... Srnooth.-. Smooth Rough smeoth Rough.

of the plywood grain. A considerable amount of concrete (3.36 gm./sq. ft.) adhered to the playwood panels.

When the plywood panels were coated with a solvent solution of resin (Composition B), the surface of the concrete was smooth and free from dust with some reflection of the plywood grain. The concrete which adhered to the plywood panels was 1.0 gm./sq. it.

When the plywood panels were coated with Compositions C and D which contained no wax and no mineral oil, respectively, the surface of the concrete was smooth with very little reflection of the plywood grain. However, there was a slight dusting effect with both Compositions C and D. While Compositions C and D showed an improvement when compared with the uncoated panel and with Compositions A and B insofar as the amount of concrete which adhered to the plywood panel was concerned, the amount was still in excess of that which is The data in Table II clearly indicate the improved results obtained with compositions of the invention, i.e., Compositions E, L, M and N. It will be noted that the amount of concrete which adhered to the plywood panels coated with Compositions E, L, M and N was quite small, i.e., 0.12, 0.36, 0.20 and 0.04 gm./sq. it, respectively. The surface of the concrete molded with forms coated with Compositions E, L, M and N were smooth. Compositions O, P and Q which contained wood rosin, limed rosin and a saturated resin, respectively, instead of a resin derived from a cyclic olefin, resulted in an undesirably large amount of concrete adhering to the panels, i.e., 4.08, 1.72 and 1.24 gm./sq. ft., respectively. Also, with Compositions O and Q, the face of the concrete slab was rough.

Other coating compositions within the scope of the invention are illustrated in Table III.

fire point, 10 F. oral oil (32.4 APT gravity; 106 US at F.; flash point, 390 F.; fire point,

+5 F.). Mineral oil (22.7 APT gravity; 509

Min

520 F.; pour point,

445 F.; pour point,

SUS at 100 F.; flash point, 410 F.; fir2eo i oint, 460 F.; pour point,

Paraflin we. (melting point, F.).. 10.0 100-...-. 10.0

Parafiin wax (melting point, F.) Stoddard solvent (47.1 API gravity; over at 340 F.; end boiling point, 382 F.; flash point, 110 F.).

Kerosene (423 API gravity; flash 62.0

point, 144 F.). Concrete form test:

Ease of removal of form Medium.. Easy Easy Easy. Concrete stuck to form, gm./sq. ft. 0.16 0. 0.20 0. Appearance of concrete Smooth.-- Smooth... Smooth... Smooth.

to be desired particularly with respect to Composition D.

When the plywood panels were coated with compositions of the invention, Compositions E to K, the surface The data in Table III clearly indicate the utility of Compositions R, S, T and U. It will be noted that the concrete slabs had a smooth appearance and that there of the concrete was smooth and free from dust with very 75 was very little adherence of the concrete to the surface of the panels coated with Compositions R, S, T and U, i.e., 0.16, 0.12, 0.20 and 0, respectively.

While my invention has been described with reference to various specific examples and embodiments, it will be understood that the invention is not limited to such examples and embodiments and may be variously practiced within the scope of the claims hereinafter made.

I claim:

1. A coating composition for applying to wooden concrete forms consisting essentially of a mixture of about 15 to about 40 percent by weight of a hydrocarbon resin derived from a cyclic olefin selected from the group consisting of cyclopentadie-ne, dicyclopentadiene, cyclohexadiene and vinyl cyclohexene, said resin having a melting point of about 50 to about 300 F.; about to about 25 percent by weight of a mineral oil having a viscosity of about 100 to about 1000 SUS at 100 F.; about to about percent by weight of a parafiin Wax having a melting point of about 120 to about 155 F.; and about 45 to about 65 percent by Weight of a hydrocarbon distillate solvent.

2. The coating composition of claim 1 wherein the hydrocarbon resin is a dicyclopentadiene resin.

3. The coating composition of claim 2 wherein the dicyclopentadiene resin has a melting point of about 50 F.

4. The coating composition of claim 2 wherein the dicyclopentadiene resin has a melting point of about 215 F.

5. The coating composition of claim 2 wherein the dicyclopentadiene resin has a melting point of about 285 F.

6. The coating composition of claim 1 wherein the hydrocarbon resin is a vinyl cyclohexene resin having a melting point of about 266 F.

7. The coating composition of claim 1 wherein the parafiin wax has a melting point of about 120 F.

8. The coating composition of claim 1 wherein the paraflin wax has a melting point of about 140 F.

9. The coating composition of claim 1 hydrocarbon distillate solvent is kerosene.

10. The coating composition of claim 1 wherein the hydrocarbon distillate solvent is Stoddard solvent.

11. A coating composition for applying to wooden concrete forms consisting essentially of a mixture of about 15 to about percent by weight of a dicyclopentadiene resin having a melting point of about 215 F.; about 5 to about 25 percent by weight of a mineral oil having a viscosity of about 100 to about 1000 SUS at 100 F; about 10 to about 15 percent by weight of a paraflin wax having a melting point of about 120 F.; and about to about percent by weight of Stoddard solvent.

12. A coating composition for applying to wooden concrete forms consisting essentially of a mixture of about 15 to about 40 percent by weight of a dicyclopentadiene resin having a melting point of about 215 F.; about 5 to about 25 percent by weight of a mineral oil having a viscosity of about to about 1000 SUS at 100 F., a flash point above about 335 F., a fire point above about 370 F. and a pour point of about 20 to about +10 F.; about 10 to about 15 percent by weight of a paraffin wax having a melting point of about F.; and about 45 to about 65 percent by weight of Stoddard solvent.

wherein the References Cited UNITED STATES PATENTS 11/1955 Marcy 26028.5

MORRIS LIEBMAN, Primary Examiner P. R. MICHL, Assistant Examiner US. Cl. X.R. ll7'5.1; 260-28.5B, 33.6A 

